He said: "We're not convinced that the way it is operating at the moment and its plans for the future represent the most efficient or the most effective way to provide aviation support to the police."

The long response times have contributed to a 45% decline in the number of hours flown since 2009 - and some officers say this has, in turn, meant an increase in criminals trying to outrun police.

The cost of a flying hour has increased from £1,335 in 2009 to £2,820 in 2016/17. Meanwhile, over the same period, the number of helicopters has decreased from 33 to 19 - with the number of bases dwindling from 31 to 15.

Mr Parr said: "We know policing is under pressure...what I wouldn't want to see if police looking at the costs of calling a helicopter and deciding not to because of increasing costs when actually it's the best thing to do."

He said, however, that "it would be asking a bit much to draw a link between slightly slower response times and criminals getting away with it".

Image:The Metropolitan Police had the fastest response time in the country. File pic